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Defect Absorption in Ge 2 Sb 2 Te 5 Phase‐Change Films
Author(s) -
Gotoh Tamihiro
Publication year - 2020
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201900278
Subject(s) - materials science , amorphous solid , absorption spectroscopy , analytical chemistry (journal) , annealing (glass) , metastability , absorption (acoustics) , spectroscopy , germanium , atmospheric temperature range , crystallography , optics , chemistry , optoelectronics , physics , organic chemistry , chromatography , quantum mechanics , composite material , silicon , meteorology
Defect absorption spectra in amorphous and crystalline Ge 2 Sb 2 Te 5 phase‐change films are investigated. Photothermal deflection spectroscopy extended to the IR region reveals subgap absorption of the Ge 2 Sb 2 Te 5 films. Subgap absorption peaks are observed around 0.480, 0.415, and 0.368 eV for as‐deposited films, around 0.475, 0.410, and 0.360 eV for 180 °C‐annealed films, and around 0.410 and 0.350 eV for 300 °C‐annealed films at room temperature. The intensity and energies of the absorption peaks vary with heat treatments in the range of 90–300 °C. Broad absorption of 0.5–0.6 eV is also observed for as‐deposited films. Based on the experimental results, the generation mechanisms of the defect levels in amorphous, metastable, and stable crystalline Ge 2 Sb 2 Te 5 are discussed.